UV systems used in pools and aquariums can operate for years, but sooner or later one simple problem appears: the lamp needs to be replaced.
Usually, this is straightforward. You find the correct model, install it, and continue operation.
But what happens when the original lamp is no longer available?
We recently faced exactly this situation with a UV system installed at a dolphinarium.
The system
The facility uses an outdoor pool for marine mammals.
Water continuously circulates through a treatment system, where UV is used as one of the disinfection stages.
The installed unit was a Triogen UVARAY CF 105, which uses a medium-pressure UV lamp.
When the original lamps needed replacement, the customer discovered that obtaining them had become difficult. Available alternatives were expensive, and delivery times were unpredictable.
So the task was to find a compatible replacement.
At first, the specifications looked simple
The original lamp had approximately the following parameters:
length: 470 mm
bulb diameter: 44 mm
power: 2.0–2.5 kW
rotating-pin base
ozone-free operation
It might seem that a lamp with the same power and similar dimensions should work.
In practice, that was not enough.
The first replacement lamp was only slightly different in length.
That small difference caused a mechanical mismatch inside the UV unit.
The lamp could not be installed correctly, and the system did not start as expected.
This was a useful reminder that UV lamp compatibility is not defined by wattage alone.
A few millimeters can make a big difference
For specialized UV equipment, several parameters have to match at the same time.
These can include:
total lamp length;
bulb diameter;
position of the electrodes;
base geometry;
pin orientation;
electrical characteristics;
ballast compatibility.
Even a small dimensional difference can make an otherwise similar lamp unusable.
In this case, the replacement had to reproduce the geometry of the original lamp much more accurately.
Creating a replacement
To understand the original design, we studied the information provided by the customer:
technical documents;
drawings;
photos;
videos;
measurements of the original lamp.
A test version was then manufactured.
The final configuration was based on a medium-pressure UV lamp with the following parameters:
model: VGPL034
power: 2.0–2.5 kW
length: around 470 mm
bulb diameter: 44 mm
rotating-pin base adapted to the CF 105
ozone-free operation
The lamp was intended to operate directly in the existing circulation system without modifying the UV reactor.
The first version still needed adjustment
The first prototype was close, but not perfect.
The overall length and pin geometry still required correction.
Instead of modifying the customer's UV system, the lamp itself was redesigned.
After the changes, a new version was installed and tested.
This time the system started normally.
The UV unit operated without startup errors, and the built-in sensors showed stable operation.
Why ozone-free operation mattered
The UV equipment was installed in a pool containing marine mammals.
For this reason, the lamp was designed for ozone-free operation.
The goal was to replace the existing UV source without changing the way the water treatment system already worked.
In applications involving aquariums, marine parks or similar facilities, this kind of compatibility can be particularly important because changes to the treatment process may affect the entire circulation system.
What happened after testing
Once the final dimensions had been confirmed, four corrected lamps were produced to replace the initial batch.
The customer later ordered additional lamps for another similar installation.
Since the final design had already been tested in the CF 105 system, the second project did not require the same development process from the beginning.
The main takeaway
This project showed something that is easy to overlook when replacing industrial UV lamps:
matching the electrical power is only part of the job.
Mechanical dimensions can be just as important.
A replacement lamp may have the correct wattage and still fail to fit or operate correctly because of:
a few millimeters of extra length;
a different pin position;
another base design;
incompatible electrical characteristics.
For older or specialized UV systems, carefully reproducing the original lamp geometry can sometimes be easier than modifying the equipment itself.
That is especially relevant when OEM replacement lamps are discontinued or difficult to obtain.
More information about this type of equipment:
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